Blood cell effects in membrane plasma separation

The blood cell and membrane properties are important in determining hemolysis and cell deposition, as shown previously, and thus are determinants of the maximum plasma separation rates. In general, membranes with large mean pore sizes exhibit hemolysis at lower operating transmembrane pressures. Surface structure and not necessarily por tortuosity has been found to be more important, at least for the hollow fiber membranes studied. Mean membrane pore data coupled with SEM observations were useful in correlating red cell lysis with membrane properties. The red cell may be likened to a liquid drop, encased by a flexible deformable membrane. Cell deformation, orientation, and rotation increase as does interfacial surface tension with rising rates of shear. A high correlation of interfacial surface tension with shear rate was determined using a filtration model incorporating cell deformability. Interfacial surface tensions of less than 6 dynes/cm for shear rates up to 1000s-1 were found. Inclusion of blood and membrane properties in the analysis of plasma separation gives significantly better fit of the experimental data to theoretical correlations than do other models which exclude their consideration.